Update: Remind me to stop reading into countdown clocks. Seems the countdown was created by fans who have been playing the "Portal 2" ARG (thanks Jim!). Hopes of pneumatic tubes dashed!
Original Story: At the launch of "Portal 2," some members of the internet through a hissy fit over the game's collection of day one downloadable content (even though it was just a bunch of hats for your co-op robots). It did make some wonder whether we'd be seeing anything more substantial by way of DLC for the game, and Valve might be answering that question in just a few hours. The developer sent this letter out to members of the press which is basically written as a memo from the offices of Aperture Science. The letter points to yet another mysterious ARG site with a countdown clock.
In the memo, there's a mention of pneumatic tube system in the Aperture office, which is offline due to "unforeseen events." Pneumatic tubes, huh? Funny! We actually remember Valve showing us something called a Pneumatic Diversity Vent at E3 which would be one of the game's many puzzle elements. As a matter of fact, you can see the vent in action for yourself in this official video. Seems odd that Valve would go to all the trouble to make such an awesome doodad and not put it in the player's hands, right?
The hope is that the countdown clock (which runs out in less than three hours) is counting down to some forthcoming DLC which will feature the Pneumatic Diversity Vent prominently. And if that is the case, it does beg the question how the DLC would be presented? Co-op or solo? Story-based? Will it be free? So many questions, so few answers! Thankfully we needn't wait long...